Multiplicative distance
In algebraic geometry, is said to be a multiplicative distance function over a field if it satisfies{{citation
| last = Hartshorne | first = Robin |author-link=Robin Hartshorne
| doi = 10.1007/978-0-387-22676-7
| isbn = 0-387-98650-2
| location = New York
| mr = 1761093
| page = 363
| publisher = Springer-Verlag
| series = Undergraduate Texts in Mathematics
| title = Geometry: Euclid and beyond
| url = https://books.google.com/books?id=EJCSL9S6la0C&pg=PA363
| year = 2000}}.